Filter device with filter disks

ABSTRACT

A filter device, particularly for filtering melt-type fluids, such as polymer melts, includes at least one filter disk having two filter disk halves connected to each other by their edges and provided with filter material on their exterior surfaces. The filter disk halves are held apart by a supporting device delimiting a substantially free hollow area between them, through which a fluid can flow freely. Inwardly, they delimit an outflow opening for the melt-type filtered fluid. The supporting device has individual supporting cams of substantially equal outer dimensions and arranged in several groups. Separated from each other, the supporting cams extend radially outwardly form the outflow opening, are rigidly connected to at least one of the two halves, and traverse the hollow area in such a way as to rest against the other filter disk half. This results in a filter device which is economical to produce and which has enhanced filter performance when in operation. It is suited particularly to filtering melt-type liquids, such as polymer melts, under high pressure.

FIELD OF THE INVENTION

The present invention relates to a filter device, especially forfiltering melt-like fluids, such as polymer melts, having at least onefilter disk made up of two filter disk halves. The filter disk halvesare connected with one another along one edge and are fitted with afabric or cloth fabric filter material aligned on the exterior. The diskhalves are held at some distance from one another by a supportarrangement to define a hollow space between them having an essentiallyopen flow-through passage. In the interior, an outlet opening isprovided for the melt-like fluid.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,902,420 discloses a filter arrangement with amulti-layer construction. Between the fabric or cloth fabric filtermaterials lying facing one another a drainage plate is inserted assupport device Longitudinal slots extend from the exterior to theinterior to define a hollow space of small volume between the fabric orcloth fabric filter materials. The medium to be filtered, for example apolymer melt, in this system is subjected to increased flow resistance,so that the filter capacity is correspondingly decreased. Because of thecomplicated construction and the multiplicity of parts, themanufacturing costs are higher. Furthermore, the separation of the fluidstreams in the filter disk occurring by the separation into variouslongitudinal slots causes the so-called memory effect. If, for instance,there is subsequent formation of blowholes or such phenomena out of thepolymer melts, this leads to undesired formations of strips or lamina.

DE-AS 1,096,331 discloses a filter device having at least one filterdisk formed of two filter disk halves connected with one another.Between them, the filter disk halves limit an essentially open passage,allowing flow-through in the hollow space. A fabric or cloth fabricfilter material is aligned on the disk halves exterior. The filter diskhalf has a metal disk with discharge openings or is constructed ofspoke-like fillets. Coiled ribs or fins or fillets are used as a supportarrangement, and extend radially inward and at some distance from oneanother over the entire hollow space, which tapers conically outward tothe exterior periphery. Insufficient support is provided for the filterdisk halves with their fabric or cloth filter material, so that thisfilter arrangement can be used only in a limited manner. Especially whenhigh pressures are present, it cannot be used without danger ofbreakdown. Additionally, the ribs or fins used in this filterarrangement separate the hollow space which is preferably open toflow-through into individual chambers. Here too, the flow resistance isincreased, so that this filter arrangement does not suffice for thefiltering of melt-like fluids.

SUMMARY OF THE INVENTION

Objects of the present invention are to provide improved filterarrangements which can be manufactured at low cost and which allow anincreased filtering capacity during operation. Especially for thefiltering of melt-like fluids, such as polymer melts, it can be designedfor use under high pressures.

The support arrangement includes individual supporting cams withessentially identical exterior dimensions. The cams extend outwardlyfrom the discharge opening, are arranged in a plurality of groups, areseparated from one another radially, are securely connected with atleast one of the two filter disk halves and pass through the hollowspace. In this manner, each filter disk half is in contact with theother filter disk half, and the entire hollow space is available as anessentially open flow-through passage. The above-described drainageplates can then be deleted to save cost. Consequently, the flow volumeof the melt-like fluid to be filtered, such as polymer melts, andconsequently also the filtering capacity, are increased.

As a result of having the plurality of supporting cams arranged ingroups, extending between the two filter disk halves of a filter diskand supporting this disk assembly, a high resistance to pressurestresses on the filter disk halves as well as on their fabric or clothfabric filter materials is attained. Overall, a highly pressure-stablefilter disk is realized for use in the filter device. Simultaneously,the offset arrangement of the supporting cams causes mixing of the meltflow, which thus counters the memory-effect.

With one preferred embodiment of the filter device according to thepresent invention, the individual group arrangements of supporting camsare arranged at different radial distances from the outlet opening andare aligned along concentric circles around this outlet opening. Such anarrangement allows a high degree of support for the filter disk halves.Accordingly, such arrangement has only a slightly negative influence onthe dimensions of the opening of the, hollow space for flow-throughbetween the filter disk halves in the sense of causing only a slightincrease of flow resistance. Also, a favorable means of manufacturingthe filter disk, and consequently the entire filter device, can beattained in this manner.

In another preferred embodiment of the filter device according to thepresent invention, the two filter disk halves of a filter disk areprovided with supporting cams of identical dimensions on the adjacentand facing sides. Such sides either engage along a longitudinalseparation line of the filter disk halves where they abut one another,and/or, wit contact with the relevant other filter disk half, theyengage in the free spaces between the supporting cams of each relevantfacing filter disk half. With such described arrangements, to save onoutlay, the filter disk can be composed of identically constructedfilter disk halves.

The outlay for the manufacture can be further decreased, insofar as thesupporting cams are connected tightly with the relevant filter diskhalves, by means of weld points produced by a projection-weld method.

With another preferred embodiment of the filter device according to thepresent invention, the two filter disk halves extend parallel to oneanother and define a disk-shaped hollow space of identical dimensions. Afavorable flow-through of the melt-like fluid is attained in thismanner, without increasing the wall shearing or thrust stresses when itcomes to the flow resistance with the flow of the melt though the filterdisk.

With one especially preferred embodiment of the filter device accordingto the present invention, the supporting cams form fillet-like solid boxprofiles. Such cams, in turn, can be mounted on the filter disk halvesin such a manner that they free the discharge openings in the filterdisk halves. As a result of the use of the solid box section profiles,the fabric or cloth fabric filter materials on the outside of the twofilter disk halves of a filter disk can be securely supported and arenot drawn into the box section profile of the supporting cams. Forexample, the filter materials could be drawn into the box sectionprofile, if the supporting cams would be shaped out of the filter diskhalves by a deepdrawing method or the like. Since the box sectionprofiles are embodied as fillet-like, they can be used beneficially inthe intermediate spaces between the openings of a filter disk half. Theythen do not have the capacity to negatively influence the openflow-through through these discharge openings. The arrangement canespecially avoid the generation of flow shadows, since the dischargeopenings are grouped without any side spacing directly around thesupporting cams and are left free.

With another especially preferred embodiment of the filter deviceaccording to the present invention, the discharge openings are formed inthe filter disk halves by means of circular cutouts. In groups ofdifferent magnitudes, the circular cutouts extend along concentriccircles around the outlet opening. By a certain selection of thegrouping with discharge openings in the form of rows of holes, the flowratios within the filter disk can improve for the melt-like fluid, andthus, the filter capacity can be increased. Preferably the filter diskhalves and the supporting cams are formed of top-grade steel, so thatthese are not inclined to corrode, and consequently, cannot pollute themelt-like fluid. Insofar as spacing cams are arranged on the top andbottom of the filter disk, especially in the peripheral side borderareas where the filter disk halves are connected with one another by aborder welding joint, then in a cost-saving manner the traditionalso-called spacer can be deleted. The known filter device would thenserve to hold the filter disks inside the assembly at some spacing fromone another Such a spacing is now realized by means of the spacing camsarranged directly on the filter disks.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses preferredembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a side elevational view in section of a filter disk accordingto an embodiment of the present invention;

FIG. 2 is a top plan view of a filter disk half, formed of a metal diskwith discharge openings, of FIG. 1;

FIG. 3 is an enlarged, side elevational view in section of the filterdisk in area X of FIG. 1; and

FIG. 4 is an enlarged side elevational view in section of the filterdisk in area Y of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

A filter disk 10 is shown in longitudinal section in FIG. 1. Filter disk10 comprises two filter disk halves 12 and 14 connected with one anotherand limiting between them a cylindrical, disk-like hollow space 16 ofidentical dimensions having an essentially open flow-through passage.Each filter disk half is provided with a fabric or cloth fabric filtermaterial 18 of predetermined mesh or pore dimensions and aligned on theexterior.

As shown particularly in FIG. 2, filter disk haves 12 and 14 are eachformed of a metal disk 20 with discharge openings, of identicalconstruction, preferably of top-grade steel. The metal disk 20 has aplurality of discharge openings 22, through which can flow the melt-likefluid, especially the polymer melts. Discharge openings 22 arepreferably in the form of circular openings and are formed on the metaldisk 20 by using different cross sectional widths of openings as shownin FIG. 3. The openings are arranged to form individual radial groups24, 26, 28 and 30. The individual groups 24, 26, 28, 30 of dischargeopenings 22 incorporate different frequency arrangements of dischargeopenings 22, and are oriented along concentric circles around thevertically oriented longitudinal midline of filter disk 10. Thus, theinnermost group 24 has discharge openings 22 on five concentric circlesaligned one behind the other. Likewise, the following group 26 hasdischarge openings 22, the group 38 having discharge openings 22, andfinally the group 30 having discharge openings 22.

In some detail, the interior of metal disk 20, with discharge openingsas shown in FIG. 2, has projecting ribs or fins or web-like fillets orfillet-like, solid box section profiles forming supporting cams 32. Thecams extend along concentric circles aligned outward and formed intogroups 34, 36, 38, 40, 42. In some detail, filter disk halves 12, 14 inthe form of the metal disk 20 with discharge openings in the interiordefines a circular outlet opening or chamber 44. The cited supportingcams are parts of a supporting arrangement 46 which holds the filterdisk halves 12, 14 at a certain, defined distance from one another andpressure-stable. Outlet opening 44 in turn represents a circular outletopening, through which the melt-like filtered fluid is discharged fromthe filter device.

The two filter disk halves 12 and 14 of filter disk 10 are provided withsupporting cams 32 of identical height and identical dimensions on theirsides facing one another. Supporting cams 32 can be arranged, in atembodiment not shown in greater detail, along the longitudinalseparation line 48 of FIG. 1, or, as shown in FIGS. 1 and 2, ondifferent plate halves, whereby supporting cams 32 extend into the openhollow space following the superpositioning of the filter disk halves 12and 14. The hollow space in turn is limited by the other filter diskhalf, either 14 or 12, only in laminar configuration. With a differentand not shown embodiment, the distribution of supporting cams 32 can bearranged appropriately for the filter disk halves 12 and 14 in such amanner that they engage alternating according to a predeterminablepattern in the intermediate spaces produced between supporting cams 32of the other filter disk half, either 14 or 12. An especially low-costmethod of manufacture, however, is when the supporting cam arrangement32 is arranged as is illustrated for the two filter disk halves 12 and14 in FIG. 2. The filter disk halves 12, 14, being identical with oneanother, need only be pivoted around the longitudinal midline orseparation line 48 of filter disk 10 and be superimposed one on theother, in order to obtain the disk assembly as in FIG. 1. At this pointlet it also be repeated that the filter disk 10 is to be referred to intechnical terminology as ‘disk’ or ‘filter disk’.

As is shown further in FIGS. 1 and 3, the metal disk 20 incorporatingdischarge openings opens to the exterior through a supporting ring 50.Ring 50 is offset from the longitudinal midline of metal disk 20 andterminates on the longitudinal midline 48 of filter disk 10. As is shownparticularly by the enlarged depiction of FIG. 3, the adjacent, facingsupporting rings 50 of a filter disk 10 are superposed one over theother and are connected tightly with one another around the exteriorperiphery by leans of a circumferential welding joint 52. Likewise, bymeans of an annular welding joint 54, the fabric or cloth fabric filtermaterial disks 18 are connected tightly on the exterior periphery withthe exterior peripheral edge of metal disk 20 having discharge openings.Possible fluid flow directions are shown in FIGS. 3 and 4 with arrows.The melt-like medium or fluid to be filtered, especially in the form ofpolymer melts, comes under high pressure (above 100 bar) from theoutside inward through the fabric or cloth fabric material 18 and isconducted through discharge openings 22 in metal disk 20 into openhollow space 16 defined therein. Since no flow resistance in hollowspace 16 is provided before reaching supporting cams 32, the overallflow resistance is considerably diminished, and the flow velocity of themedium through the filter device and consequently also the filtrationcapacity are commensurately increased.

The sectional enlargement of area, indicated with “Y” from FIG. 1 andshown in FIG. 4, shows the possible flow direction of filter disk 10 tooutlet opening 44 with arrows. The relevant discharge chamber or therelevant outlet opening 44 in the interior of each filter disk 10 islimited by an interior supporting ring 56 on each filter disk half 12and 14. The disk thickness in this area is maintained essentiallyidentical. The interior supporting rings 56 of each filter disk 10 areopposite and adjacent to one another and are held at a predetermineddistance from one another by means of a spacing disk or washer 58,especially in the form of a type of flow gasket The fabric or clothfabric material 18 is then tightly connected by means of an interiorwelding joint 60 with the associated interior supporting ring 56. Theoutward-projecting part of supporting ring 56 forms a contact surfacefor the interior edge of the fabric or cloth fabric filter material 18to be supported.

The individual supporting cams 32 are tightly connected with therelevant filter disk halves 12 and/or 14 by welding points 62 producedby means of a projection weld method. By means of other welding points64 produced by a projection weld method, the interior of metal disk 20facing and adjacent to outlet opening 44 is tightly welded with thealready cited interior supporting rings 56. On the top 66 and bottom 68of each filter disk 10, spacing cams 70 are then arranged in uniform,radial spacings around the exterior periphery spaced from one another onfilter disk 10. Spacing cams 70 are mounted securely by means ofprojection weld points 72 and the function as a spacer for individualfilter disks 10. Such spacing cams 70, as also shown in FIG. 1, could bedistributed over the filter disk top surface, or especially could bearranged in the middle area.

A plurality of filter disks 10 arranged one over the other then providethe complete filter device arranged in a housing, not shown completely.With the relevant filter disk 10, a considerably lower pressure isrequired for overcoming interior resistance. Additionally, themanufacturing costs are considerably lowered by the simplifiedconstruction. Since the individual supporting cams 32 are terminated attheir open ends in a circular sealing off, the flow behavior for themelt-like fluid which is to be filtered is improve& Furthermore, sincethe relevant supporting cam 32 is limited by each group of six circulardischarge openings 22, the discharge openings 22 are not covered and arecompletely accessible for input of the medium.

While various embodiments have been chosen to illustrate the invention,it will be understood by those skilled in the at that various changesand modifications can be made therein without departing from the scopeof the invention as defined in the appended claims.

What is claimed is:
 1. A filter device for filtering melt-like fluids,comprising: at least one filter disk including first and second filterdisk halves connected along one edge of each and having dischargeopenings therein; a fabric filter material on an exterior of each ofsaid filter disk halves; an outlet opening for the filtered fluid atinterior limits of said filter disk halves; and a support arrangementholding said filter disk halves at a distance from one another to definea hollow space therebetween having an essentially open flow throughpassage, said support arrangement including individual supporting camswith essentially identical exterior dimensions, said supporting camsbeing arranged in a plurality of groups and separated from one another,extending radially outwardly from said outlet opening, being fixedlyconnected with at least one of said filter disk halves and passingthrough said hollow space to contact the other of said filter diskhalves, said supporting cams being formed as solid box section profilesoffset on one of said filter disk halves to free said dischargeopenings, said supporting cams having identical dimensions and beingprovided on sides of said filter disk halves facing one another, saidsupporting cams on one of said filter disk halves abutting saidsupporting cams on the other of said filter disks along a longitudinalseparation line between said filter disk halves.
 2. A filter deviceaccording to claim 1 wherein each of said groups of said supporting camsare located at different radial distances from said outlet opening, withsaid supporting cams of each of said groups located on a circle centeredon said outlet opening.
 3. A filter device according to claim 1 whereinsaid first and second filter disk halves with said supporting camsthereon are identical.
 4. A filter device according to claim 1 whereinsaid supporting cams are fixedly connected to the respective filter diskhalves by welding points produced by a projection weld method.
 5. Afilter device according to claim 1 wherein said filter disk halvesextend parallel to one another and define said hollow space therebetweenof identical dimensions.
 6. A filter device according to claim 1 whereinsaid discharge openings comprise circular cutouts arranged in groups ofdifferent magnitudes of frequency and along circles concentric with saidoutlet opening.
 7. A filter device according to claim 1 wherein saidfilter disk halves and said supporting cams are formed of top-gradesteel.
 8. A filter device according to claim 1 wherein said first andsecond filter disk halves comprise spacing cams extending in oppositedirections from exterior surfaces of said filter disk halves adjacent aperiphery thereof where said filter disk halves are connected by acircumferential welding joint.
 9. A filter device according to claim 1wherein said first and second filter disk halves are essentiallyidentical; and each of said first and second disk halves has supportingcams on only one side of an interior surface thereof.
 10. A filterdevice according to claim 1 wherein said supporting cams arefillet-shaped.
 11. A filter device according to claim 1 wherein saidsupporting cams are narrow members with longer dimensions thereof inradial directions of said disk halves.
 12. A filter device for filteringmelt-like fluids, comprising: at least one filter disk including firstand second filter disk halves connected along one edge of each andhaving discharge openings therein; a fabric filter material on anexterior of each of said filter disk halves; an outlet opening for thefiltered fluid at interior limits of said filter disk halves; and asupport arrangement holding said filter disk halves at a distance fromone another to define a hollow space therebetween having an essentiallyopen flow through passage, said support arrangement including individualsupporting cams with essentially identical exterior dimensions, saidsupporting cams being arranged in a plurality of groups and separatedfrom one another, extending radially outwardly from said outlet opening,being fixedly connected with at least one of said filter disk halves andpassing through said hollow space to contact the other of said filterdisk halves, said supporting cams being formed as solid box sectionprofiles offset on one of said filter disk halves to free said dischargeopenings, said supporting cams on each of said filter disk halvescontacting the other of said filter disk halves in free spaces betweensaid supporting cams on said other of said filter disk halves.
 13. Afilter device according to claim 12 wherein each of said groups of saidsupporting cams are located at different radial distances from saidoutlet opening, with said supporting cams of each of said groups locatedon a circle centered on said outlet opening.
 14. A filter deviceaccording to claim 12 wherein said first and second filter disk halveswith said supporting cams thereon are identical.
 15. A filter deviceaccording to claim 12 wherein said supporting cams are fixedly connectedto the respective filter disk halves by welding points produced by aprojection weld method.
 16. A filter device according to claim 12wherein said filter disk halves extend parallel to one another anddefine said hollow space therebetween of identical dimensions.
 17. Afilter device according to claim 12 wherein said discharge openingscomprise circular cutouts arranged in groups of different magnitudes offrequency and along circles concentric with said outlet opening.
 18. Afilter device according to claim 12 wherein said filter disk halves andsaid supporting cams are formed of top-grade steel.
 19. A filter deviceaccording to claim 12 wherein said first and second filter disk halvescomprise spacing cams extending in opposite directions from exteriorsurfaces of said filter disk halves adjacent a periphery thereof wheresaid filter disk halves are connected by a circumferential weldingjoint.
 20. A filter device according to claim 12 wherein said first andsecond filter disk halves are essentially identical; and each of saidfirst and second disk halves has supporting cams on only one side of aninterior surface thereof.
 21. A filter device according to claim 12wherein said supporting cams are fillet-shaped.
 22. A filter deviceaccording to claim 12 wherein said supporting cams are narrow memberswith longer dimensions thereof in radial directions of said disk halves.23. A filter device for filtering melt-like fluids, comprising: at leastone filter disk including first and second filter disk halves connectedalong one edge of each and having discharge openings therein; a fabricfilter material on an exterior of each of said filter disk halves; anoutlet opening for the filtered fluid at interior limits of said filterdisk halves; and a support arrangement holding said filter disk halvesat a distance from one another to define a hollow space therebetweenhaving an essentially open flow through passage, said supportarrangement including individual supporting cams with essentiallyidentical exterior dimensions, said supporting cams being arranged in aplurality of groups and separated from one another, extending radiallyoutwardly from said outlet opening, being fixedly connected with saidfilter disk halves and passing through said hollow space to contact theother of said filter disk halves, said supporting cams being formed assolid box section profiles offset on both filter disk halves to freesaid discharge openings, said first and second filter disk halves withsaid supporting cams thereon being identical.
 24. A filter deviceaccording to claim 23 wherein each of said groups of said supportingcams are located at different radial distances from said outlet opening,with said supporting cams of each of said groups located on a circlecentered on said outlet opening.
 25. A filter device according to claim23 wherein said supporting cams are fixedly connected to the respectivefilter disk halves by welding points produced by a projection weldmethod.
 26. A filter device according to claim 23 wherein said filterdisk halves extend parallel to one another and define said hollow spacetherebetween of identical dimensions.
 27. A filter device according toclaim 23 wherein said discharge openings comprise circular cutoutsarranged in groups of different magnitudes of frequency and alongcircles concentric with said outlet opening.
 28. A filter deviceaccording to claim 23 wherein said filter disk halves and saidsupporting cams are formed of top-grade steel.
 29. A filter deviceaccording to claim 23 wherein said first and second filter disk halvescomprise spacing cams extending in opposite directions from exteriorsurfaces of said filter disk halves adjacent a periphery thereof wheresaid filter disk halves are connected by a circumferential weldingjoint.
 30. A filter device according to claim 23 wherein each of saidfirst and second disk halves has supporting cams on only one side of aninterior surface thereof.
 31. A filter device according to claim 23wherein said supporting cams are fillet-shaped.
 32. A filter deviceaccording to claim 23 wherein said supporting cams are narrow memberswith longer dimensions thereof in radial directions of said disk halves.33. A filter device for filtering melt-like fluids, comprising: at leastone filter disk including essentially identical first and second filterdisk halves connected along one edge of each and having dischargeopenings therein; a fabric filter material on an exterior of each ofsaid filter disk halves; an outlet opening for the filtered fluid atinterior limits of said filter disk halves; and a support arrangementholding said filter disk halves at a distance from one another to definea hollow space therebetween having an essentially open flow throughpassage, said support arrangement including individual supporting camswith essentially identical exterior dimensions, said supporting camsbeing arranged in a plurality of groups and separated from one another,extending radially outwardly from said outlet opening, being fixedlyconnected with at least one of said filter disk halves and passingthrough said hollow space to contact the other of said filter diskhalves, said supporting cams being formed as solid box section profilesoffset on one of said filter disk halves to free said dischargeopenings, each of said first and second disk halves having supportingcams on only one side of an interior surface thereof.
 34. A filterdevice according to claim 33 wherein each of said groups of saidsupporting cams are located at different radial distances from saidoutlet opening, with said supporting cams of each of said groups locatedon a circle centered on said outlet opening.
 35. A filter deviceaccording to claim 33 wherein said supporting cams are fixedly connectedto the respective filter disk halves by welding points produced by aprojection weld method.
 36. A filter device according to claim 33wherein said filter disk halves extend parallel to one another anddefine said hollow space therebetween of identical dimensions.
 37. Afilter device according to claim 33 wherein said discharge openingscomprise circular cutouts arranged in groups of different magnitudes offrequency and along circles concentric with said outlet opening.
 38. Afilter device according to claim 33 wherein said filter disk halves andsaid supporting cams are formed of top-grade steel.
 39. A filter deviceaccording to claim 33 wherein said first and second filter disk halvescomprise spacing cams extending in opposite directions from exteriorsurfaces of said filter disk halves adjacent a periphery thereof wheresaid filter disk halves are connected by a circumferential weldingjoint.
 40. A filter device according to claim 23 wherein said supportingcams are fillet-shaped.
 41. A filter device according to claim 33wherein said supporting cams are narrow members with longer dimensionsthereof in radial directions of said disk halves.